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Acoustic emission measurements on PWR weld material with inserted defects
ND T Abstracts sponsored by the German Government or by KWU. Thus a broad basis of knowledge and experience is available to define and specify ability, advantages and limits of the method. A summary of on- site tests and research programs their goals and results are given. 40521
Cole, P.T.
1987 Acoustic emission technology and economics applied to p r e s s u r e vessels and storage t a n k s Proceedings of the 16th European Working Group on Acoustic Emission Conference, London (United Kingdom), 13-18 Sep. 1987, pp. 2898-2905. Eziited by C.B. Scruby and R. Hill, Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987, Vol. 4, Pergamon Press, 1988 The most significant development in acoustic emission (hE) testing of pressure vessels and storage tanks recently has been the introduction of systems and software developed specifically for the task, rather than general purpose AE systems being used, which has been the practice to date. This change resulted from Monsanto's vast experience in testing metal vessels with AE and their development of standard procedures and severity analysis methods. The resulting MONPAC TM technology removes much of the operator dependence and, more importantly, standardises test and analysis methods, which now require significantly less experienced operators. The author (who has been running an AE test service for seven years) has been introducing MONPAC TM technology to his petrochemical customers and discusses the implication, and cost savings that can be made, in this field of condition monitoring for static plant. 40519 Hill, R.; Cowking, A.; Carswell, W.S. An acoustic emission study of stress corrosion c r a c k i n g in GFRP Proceedings of the 16th European Working Group on Acoustic Emission Conference, London (United Kingdom), 13-18 Sep. 1987, pp. 2872-2880. Edited by C.B. Scruby and R. Hill, Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987, Vol. 4, Pergamon Press, 1988 Tensile stress corrosion cracking in E-glass/polyester chopped strand mat (CSM) has been investigated via the acoustic emission (AE) produced during crack growth. Single cracks were initiated in notched specimens in an environment of aqueous sulphuric acid at room temperature. The results indicate that the number of recorded AE events during stress corrosion cracking was less than the number of fibre fractures. The total number of AE signals in this localised cracking provides a measure of the residual strength of the CSM samples. Studies of fracture surfaces, together with the AE results, indicate that the stress corrosion crack in CSM does not maintain a linear front but advances along easier (i.e. fibre-rich) pathways; this is consistent with the observation that penetration of acids through (GFRP) glass fibre reinforced plastic vessels and tanks can occur at times well before predicted failure. The results are discussed with reference to structural studies of the material and the prediction of fracture mechanics, and are compared and contrasted with other work on stress corrosion crack growth in GFRP.
40376 Odnopozov, L.Yu.; Golokhvastov, AJ~. Possible predictions for the fitness of small pressure vessels by an acoustic-emission method Soviet Journal of Nondestructive Testing, Vol. 23, No. 11, pp. 779-784 (Nov. 1988) Based on the results of experimental studies on acoustic emission when loading specimens made from high-strength steel it has been established that acoustic emission is only generated at the moment when local volumes become plastically strained. The time function of acoustic- emission parameters indicates the mechanism by which local volumes reach the stage of plastic strain owing to the nature of the loading action and the constantly changing ratio during loading for the volumes of regions with elastic and plastic strains. A low-strength structural state of a material is characterized by a decline of its acoustic- emission properties as compared with a high strength structural state. The data obtained are important to formulate properly the problem of predicting fitness for work in the case of small-sized pressure vessels properly. 39977 Kalyanasundaram, P.; Jayakumar, T.; Raj, B.; Murthy, C.R.L.; Krishnan, A.
Acoustic emission technique for leak detection in an end shield of a pressurised heavy water r e a c t o r International Journal of Pressure Vessels and Piping, Voi. 36, No. 1, pp. 65-74 (1989) This paper discusses a successful application of the Acoustic Emission Technique (AET) for the detection and location of leak paths present on an inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air- and water-leak AE signals have different characteristic features. Baseline data was generated from a sound end shield of a PHWR for characterising the background noise. A mock-up end shield system with saw-cut leak paths was used to verify the validity of the methodology. It was found that air-leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of defective end shield were acquired and analysed. It was possible to detect and locate leak paths. The presence of detected leak paths was further contrtrmed by an alternative tesL 39972
Scruby, C.B.; Stacey, K.A.
Acoustic emission measurements on PWR weld material with inserted defects Journal of Acoustic Emission, Vol. 7, No. 2, pp. 81-93 (Apr.-Jun. 1988) Ten specimens of A533B pressure vessel steel containing realistic welding defects have been monitored for acoustic emission during monotonic loading. The detection system consisted of an array of four point-contact broad-band transducers whose outputs were fed via broadband amplifiers into a multi-channel digital recording system. Specimens containing cracks, slag inclusions and porosity all generated copious emission over a range of loads, while defect-free specimens only emitted when general yield had been reached. Three-dimensional location techniques have been urea to 'image' the diffeaent types of defect and show how the concena-ation of stress, as evidenced by emission activity, moved to different regions of the defect during testing. Only limited analysis using source radiation patterns was possible, which confirmed the events to have broadly the character of mode I crack opening.
Each entry in NDT Abstracts consists of the serial number in the National NDT Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, author's names and the title of foreign journals have been transliterated into the Latin alphabet according to British Standard BS 2979 : 1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonviile Road, London N1 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availability of Publications
Information-retrievalService
Most papers listed may be obtained as loans or copies via local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's UK and International Services may be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
322
NDT&E International Volume 26 Number 6 1993
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both UK and overseas organizations through the National NDT Centre's Qualtis Subscription Scheme - further details are available from Phil Lawrence on Abingdon (0235) 433391. © 1993 United Kingdom Atomic Energy Authority
Cole, P.T.
1987 Acoustic emission technology and economics applied to p r e s s u r e vessels and storage t a n k s Proceedings of the 16th European Working Group on Acoustic Emission Conference, London (United Kingdom), 13-18 Sep. 1987, pp. 2898-2905. Eziited by C.B. Scruby and R. Hill, Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987, Vol. 4, Pergamon Press, 1988 The most significant development in acoustic emission (hE) testing of pressure vessels and storage tanks recently has been the introduction of systems and software developed specifically for the task, rather than general purpose AE systems being used, which has been the practice to date. This change resulted from Monsanto's vast experience in testing metal vessels with AE and their development of standard procedures and severity analysis methods. The resulting MONPAC TM technology removes much of the operator dependence and, more importantly, standardises test and analysis methods, which now require significantly less experienced operators. The author (who has been running an AE test service for seven years) has been introducing MONPAC TM technology to his petrochemical customers and discusses the implication, and cost savings that can be made, in this field of condition monitoring for static plant. 40519 Hill, R.; Cowking, A.; Carswell, W.S. An acoustic emission study of stress corrosion c r a c k i n g in GFRP Proceedings of the 16th European Working Group on Acoustic Emission Conference, London (United Kingdom), 13-18 Sep. 1987, pp. 2872-2880. Edited by C.B. Scruby and R. Hill, Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987, Vol. 4, Pergamon Press, 1988 Tensile stress corrosion cracking in E-glass/polyester chopped strand mat (CSM) has been investigated via the acoustic emission (AE) produced during crack growth. Single cracks were initiated in notched specimens in an environment of aqueous sulphuric acid at room temperature. The results indicate that the number of recorded AE events during stress corrosion cracking was less than the number of fibre fractures. The total number of AE signals in this localised cracking provides a measure of the residual strength of the CSM samples. Studies of fracture surfaces, together with the AE results, indicate that the stress corrosion crack in CSM does not maintain a linear front but advances along easier (i.e. fibre-rich) pathways; this is consistent with the observation that penetration of acids through (GFRP) glass fibre reinforced plastic vessels and tanks can occur at times well before predicted failure. The results are discussed with reference to structural studies of the material and the prediction of fracture mechanics, and are compared and contrasted with other work on stress corrosion crack growth in GFRP.
40376 Odnopozov, L.Yu.; Golokhvastov, AJ~. Possible predictions for the fitness of small pressure vessels by an acoustic-emission method Soviet Journal of Nondestructive Testing, Vol. 23, No. 11, pp. 779-784 (Nov. 1988) Based on the results of experimental studies on acoustic emission when loading specimens made from high-strength steel it has been established that acoustic emission is only generated at the moment when local volumes become plastically strained. The time function of acoustic- emission parameters indicates the mechanism by which local volumes reach the stage of plastic strain owing to the nature of the loading action and the constantly changing ratio during loading for the volumes of regions with elastic and plastic strains. A low-strength structural state of a material is characterized by a decline of its acoustic- emission properties as compared with a high strength structural state. The data obtained are important to formulate properly the problem of predicting fitness for work in the case of small-sized pressure vessels properly. 39977 Kalyanasundaram, P.; Jayakumar, T.; Raj, B.; Murthy, C.R.L.; Krishnan, A.
Acoustic emission technique for leak detection in an end shield of a pressurised heavy water r e a c t o r International Journal of Pressure Vessels and Piping, Voi. 36, No. 1, pp. 65-74 (1989) This paper discusses a successful application of the Acoustic Emission Technique (AET) for the detection and location of leak paths present on an inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air- and water-leak AE signals have different characteristic features. Baseline data was generated from a sound end shield of a PHWR for characterising the background noise. A mock-up end shield system with saw-cut leak paths was used to verify the validity of the methodology. It was found that air-leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of defective end shield were acquired and analysed. It was possible to detect and locate leak paths. The presence of detected leak paths was further contrtrmed by an alternative tesL 39972
Scruby, C.B.; Stacey, K.A.
Acoustic emission measurements on PWR weld material with inserted defects Journal of Acoustic Emission, Vol. 7, No. 2, pp. 81-93 (Apr.-Jun. 1988) Ten specimens of A533B pressure vessel steel containing realistic welding defects have been monitored for acoustic emission during monotonic loading. The detection system consisted of an array of four point-contact broad-band transducers whose outputs were fed via broadband amplifiers into a multi-channel digital recording system. Specimens containing cracks, slag inclusions and porosity all generated copious emission over a range of loads, while defect-free specimens only emitted when general yield had been reached. Three-dimensional location techniques have been urea to 'image' the diffeaent types of defect and show how the concena-ation of stress, as evidenced by emission activity, moved to different regions of the defect during testing. Only limited analysis using source radiation patterns was possible, which confirmed the events to have broadly the character of mode I crack opening.
Each entry in NDT Abstracts consists of the serial number in the National NDT Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, author's names and the title of foreign journals have been transliterated into the Latin alphabet according to British Standard BS 2979 : 1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonviile Road, London N1 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availability of Publications
Information-retrievalService
Most papers listed may be obtained as loans or copies via local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's UK and International Services may be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
322
NDT&E International Volume 26 Number 6 1993
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both UK and overseas organizations through the National NDT Centre's Qualtis Subscription Scheme - further details are available from Phil Lawrence on Abingdon (0235) 433391. © 1993 United Kingdom Atomic Energy Authority